Methods, wireless communications networks and infrastructure equipment

ABSTRACT

A method of controlling communications within a wireless communications network is provided. The method comprises receiving, at a first infrastructure equipment acting as a donor node connected to a core network part of a wireless communications network, signals representing data from one or more others of infrastructure equipment, the data having been received at the one or more others of the infrastructure equipment from one or more communications devices or from other infrastructure equipment, and transmitting, by the first infrastructure equipment, the data from the one or more others of the infrastructure equipment to the core network part of the wireless communications network. At least one of the infrastructure equipment uses at least one spectral efficiency enhancing technique to receive the signals, the at least one spectral efficiency enhancing technique allowing the at least one infrastructure equipment to receive the signals in the backhaul communications link.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.17/046,325, filed Oct. 9, 2020, which is based on PCT filingPCT/EP2019/059546, filed Apr. 12, 2019, which claims priority to EP18167380.7, filed Apr. 13, 2018, the entire contents of each areincorporated herein by reference.

BACKGROUND Field of Disclosure

The present disclosure relates to methods and apparatus for thecommunication of signals between various infrastructure equipment,communications devices and the core network on a wireless backhaulcommunications link in a wireless communications system.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Recent generation mobile telecommunication systems, such as those basedon the 3GPP defined UMTS and Long Term Evolution (LTE) architectures,are able to support a wider range of services than simple voice andmessaging services offered by previous generations of mobiletelecommunication systems. For example, with the improved radiointerface and enhanced data rates provided by LTE systems, a user isable to enjoy high data rate applications such as mobile video streamingand mobile video conferencing that would previously only have beenavailable via a fixed line data connection. In addition to supportingthese kinds of more sophisticated services and devices, it is alsoproposed for newer generation mobile telecommunication systems tosupport less complex services and devices which make use of the reliableand wide ranging coverage of newer generation mobile telecommunicationsystems without necessarily needing to rely on the high data ratesavailable in such systems. The demand to deploy such networks istherefore strong and the coverage area of these networks, i.e.geographic locations where access to the networks is possible, may beexpected to increase ever more rapidly.

Future wireless communications networks will therefore be expected toroutinely and efficiently support communications with a wider range ofdevices associated with a wider range of data traffic profiles and typesthan current systems are optimised to support. For example it isexpected future wireless communications networks will be expected toefficiently support communications with devices including reducedcomplexity devices, machine type communication (MTC) devices, highresolution video displays, virtual reality headsets and so on. Some ofthese different types of devices may be deployed in very large numbers,for example low complexity devices for supporting the “The Internet ofThings”, and may typically be associated with the transmissions ofrelatively small amounts of data with relatively high latency tolerance.

In view of this there is expected to be a desire for future wirelesscommunications networks, for example those which may be referred to as5G or new radio (NR) system/new radio access technology (RAT) systems,as well as future iterations/releases of existing systems, toefficiently support connectivity for a wide range of devices associatedwith different applications and different characteristic data trafficprofiles.

As radio technologies continue to improve, for example with thedevelopment of 5G, the possibility arises for these technologies to beused not only by infrastructure equipment to provide service to wirelesscommunications devices in a cell, but also for interconnectinginfrastructure equipment to provide a wireless backhaul. In view of thisthere is a need to ensure that a donor infrastructure equipment that isphysically connected to the core network does not suffer from a“capacity crunch” when a large amount of data is being transmitted fromvarious communications devices and infrastructure equipment to the corenetwork via the donor infrastructure equipment.

SUMMARY OF THE DISCLOSURE

The present disclosure can help address or mitigate at least some of theissues discussed above as defined in the appended claims.

Embodiments of the present technique can provide a method of controllingcommunications within a wireless communications network. The wirelesscommunications network comprises a plurality of infrastructure equipmenteach being configured to communicate with one or more others of theinfrastructure equipment via a backhaul communications link, one or moreof the infrastructure equipment each being configured to communicatewith one or more communications devices via an access link. The methodcomprises receiving, at a first of the infrastructure equipment actingas a donor node connected to a core network part of the wirelesscommunications network, signals representing data from one or moreothers of the infrastructure equipment, the data having been received atthe one or more others of the infrastructure equipment from one or moreof the communications devices or from other infrastructure equipment,and transmitting, by the first infrastructure equipment, the data fromthe one or more others of the infrastructure equipment to the corenetwork part of the wireless communications network. At least one of theinfrastructure equipment uses at least one spectral efficiency enhancingtechnique to receive the signals, the at least one spectral efficiencyenhancing technique allowing the at least one infrastructure equipmentto receive the signals in the backhaul communications link, the at leastone spectral efficiency enhancing technique not allowing the at leastone infrastructure equipment to receive the signals in the access link.

Respective aspects and features of the present disclosure are defined inthe appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 schematically represents some aspects of a LTE-type wirelesstelecommunication system which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 2 schematically represents some aspects of a new radio accesstechnology (RAT) wireless communications system which may be configuredto operate in accordance with certain embodiments of the presentdisclosure;

FIG. 3 is a schematic block diagram of some components of the wirelesscommunications system shown in FIG. 2 in more detail in order toillustrate example embodiments of the present technique;

FIG. 4 schematically represents some aspects of an example wirelesstelecommunication network which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 5 is reproduced from [3], and provides a first example of anIntegrated Access and Backhaul (IAB) deployment scenario;

FIG. 6 is reproduced from [5], and provides a second example of an IABdeployment scenario in which there are multiple candidate routes eachcomprising multiple hops from the end node to the donor node;

FIG. 7 is a block diagram illustrating a first possible networkarchitecture for providing a wireless backhaul by means of IAB in awireless telecommunication network which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 8 is a block diagram illustrating a second possible networkarchitecture for providing a wireless backhaul by means of IAB in awireless telecommunication network which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 9 is a block diagram illustrating a third possible networkarchitecture for providing a wireless backhaul by means of IAB in awireless telecommunication network which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 10 shows a part schematic, part message flow diagram ofcommunications in a wireless communications system in accordance withembodiments of the present technique; and

FIG. 11 shows a flow diagram illustrating a process of communications ina communications system in accordance with embodiments of the presenttechnique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Long Term Evolution (LTE) Wireless Communications System

FIG. 1 provides a schematic diagram illustrating some basicfunctionality of a mobile telecommunications network/system 6 operatinggenerally in accordance with LTE principles, but which may also supportother radio access technologies, and which may be adapted to implementembodiments of the disclosure as described herein. Various elements ofFIG. 1 and certain aspects of their respective modes of operation arewell-known and defined in the relevant standards administered by the3GPP® body, and also described in many books on the subject, forexample, Holma H. and Toskala A [1]. It will be appreciated thatoperational aspects of the telecommunications networks discussed hereinwhich are not specifically described (for example in relation tospecific communication protocols and physical channels for communicatingbetween different elements) may be implemented in accordance with anyknown techniques, for example according to the relevant standards andknown proposed modifications and additions to the relevant standards.

The network 6 includes a plurality of base stations 1 connected to acore network 2. Each base station provides a coverage area 3 (i.e. acell) within which data can be communicated to and from communicationsdevices 4.

Although each base station 1 is shown in FIG. 1 as a single entity, theskilled person will appreciate that some of the functions of the basestation may be carried out by disparate, inter-connected elements, suchas antennas, remote radio heads, amplifiers, etc. Collectively, one ormore base stations may form a radio access network.

Data is transmitted from base stations 1 to communications devices 4within their respective coverage areas 3 via a radio downlink. Data istransmitted from communications devices 4 to the base stations 1 via aradio uplink. The core network 2 routes data to and from thecommunications devices 4 via the respective base stations 1 and providesfunctions such as authentication, mobility management, charging and soon. Terminal devices may also be referred to as mobile stations, userequipment (UE), user terminal, mobile radio, communications device, andso forth.

Services provided by the core network 2 may include connectivity to theinternet or to external telephony services. The core network 2 mayfurther track the location of the communications devices 4 so that itcan efficiently contact (i.e. page) the communications devices 4 fortransmitting downlink data towards the communications devices 4.

Base stations, which are an example of network infrastructure equipment,may also be referred to as transceiver stations, nodeBs, e-nodeBs, eNB,g-nodeBs, gNB and so forth. In this regard different terminology isoften associated with different generations of wirelesstelecommunications systems for elements providing broadly comparablefunctionality. However, certain embodiments of the disclosure may beequally implemented in different generations of wirelesstelecommunications systems, and for simplicity certain terminology maybe used regardless of the underlying network architecture. That is tosay, the use of a specific term in relation to certain exampleimplementations is not intended to indicate these implementations arelimited to a certain generation of network that may be most associatedwith that particular terminology.

New Radio Access Technology (5G) Wireless Communications System

An example configuration of a wireless communications network which usessome of the terminology proposed for NR and 5G is shown in FIG. 2 . A3GPP Study Item (SI) on New Radio Access Technology (NR) has beendefined [2]. In FIG. 2 a plurality of transmission and reception points(TRPs) 10 are connected to distributed control units (DUs) 41, 42 by aconnection interface represented as a line 16. Each of the TRPs 10 isarranged to transmit and receive signals via a wireless access interfacewithin a radio frequency bandwidth available to the wirelesscommunications network. Thus within a range for performing radiocommunications via the wireless access interface, each of the TRPs 10,forms a cell of the wireless communications network as represented by acircle 12. As such, wireless communications devices 14 which are withina radio communications range provided by the cells 12 can transmit andreceive signals to and from the TRPs 10 via the wireless accessinterface. Each of the distributed units 41, 42 are connected to acentral unit (CU) 40 (which may be referred to as a controlling node)via an interface 46. The central unit 40 is then connected to the a corenetwork 20 which may contain all other functions required to transmitdata for communicating to and from the wireless communications devicesand the core network 20 may be connected to other networks 30.

The elements of the wireless access network shown in FIG. 2 may operatein a similar way to corresponding elements of an LTE network asdescribed with regard to the example of FIG. 1 . It will be appreciatedthat operational aspects of the telecommunications network representedin FIG. 2 , and of other networks discussed herein in accordance withembodiments of the disclosure, which are not specifically described (forexample in relation to specific communication protocols and physicalchannels for communicating between different elements) may beimplemented in accordance with any known techniques, for exampleaccording to currently used approaches for implementing such operationalaspects of wireless telecommunications systems, e.g. in accordance withthe relevant standards.

The TRPs 10 of FIG. 2 may in part have a corresponding functionality toa base station or eNodeB of an LTE network. Similarly the communicationsdevices 14 may have a functionality corresponding to the UE devices 4known for operation with an LTE network. It will be appreciatedtherefore that operational aspects of a new RAT network (for example inrelation to specific communication protocols and physical channels forcommunicating between different elements) may be different to thoseknown from LTE or other known mobile telecommunications standards.However, it will also be appreciated that each of the core networkcomponent, base stations and communications devices of a new RAT networkwill be functionally similar to, respectively, the core networkcomponent, base stations and communications devices of an LTE wirelesscommunications network.

In terms of broad top-level functionality, the core network 20 connectedto the new RAT telecommunications system represented in FIG. 2 may bebroadly considered to correspond with the core network 2 represented inFIG. 1 , and the respective central units 40 and their associateddistributed units/TRPs 10 may be broadly considered to providefunctionality corresponding to the base stations 1 of FIG. 1 . The termnetwork infrastructure equipment/access node may be used to encompassthese elements and more conventional base station type elements ofwireless telecommunications systems. Depending on the application athand the responsibility for scheduling transmissions which are scheduledon the radio interface between the respective distributed units and thecommunications devices may lie with the controlling node/central unitand/or the distributed units/TRPs. A communications device 14 isrepresented in FIG. 2 within the coverage area of the firstcommunication cell 12. This communications device 14 may thus exchangesignalling with the first central unit 40 in the first communicationcell 212 via one of the distributed units 10 associated with the firstcommunication cell 12.

It will further be appreciated that FIG. 2 represents merely one exampleof a proposed architecture for a new RAT based telecommunications systemin which approaches in accordance with the principles described hereinmay be adopted, and the functionality disclosed herein may also beapplied in respect of wireless telecommunications systems havingdifferent architectures.

Thus certain embodiments of the disclosure as discussed herein may beimplemented in wireless telecommunication systems/networks according tovarious different architectures, such as the example architectures shownin FIGS. 1 and 2 . It will thus be appreciated the specific wirelesstelecommunications architecture in any given implementation is not ofprimary significance to the principles described herein. In this regard,certain embodiments of the disclosure may be described generally in thecontext of communications between network infrastructureequipment/access nodes and a communications device, wherein the specificnature of the network infrastructure equipment/access node and thecommunications device will depend on the network infrastructure for theimplementation at hand. For example, in some scenarios the networkinfrastructure equipment/access node may comprise a base station, suchas an LTE-type base station 1 as shown in FIG. 1 which is adapted toprovide functionality in accordance with the principles describedherein, and in other examples the network infrastructure equipment maycomprise a control unit/controlling node 40 and/or a TRP 10 of the kindshown in FIG. 2 which is adapted to provide functionality in accordancewith the principles described herein.

A more detailed diagram of some of the components of the network shownin FIG. 2 is provided by FIG. 3 . In FIG. 3 , a TRP 10 as shown in FIG.2 comprises, as a simplified representation, a wireless transmitter 30,a wireless receiver 32 and a controller or controlling processor 34which may operate to control the transmitter 30 and the wirelessreceiver 32 to transmit and receive radio signals to one or more UEs 14within a cell 12 formed by the TRP 10. As shown in FIG. 3 , an exampleUE 14 is shown to include a corresponding transmitter 49, a receiver 48and a controller 44 which is configured to control the transmitter 49and the receiver 48 to transmit signals representing uplink data to thewireless communications network via the wireless access interface formedby the TRP 10 and to receive downlink data as signals transmitted by thetransmitter 30 and received by the receiver 48 in accordance with theconventional operation.

The transmitters 30, 49, the receivers 32, 48 may include radiofrequency filters and amplifiers as well as signal processing componentsand devices in order to transmit and receive radio signals in accordancefor example with the 5G/NR standard. The controllers 34, 44 may be, forexample, a microprocessor, a CPU, or a dedicated chipset, etc.,configured to carry out instructions which are stored on a computerreadable medium, such as a non-volatile memory. The processing stepsdescribed herein may be carried out by, for example, a microprocessor inconjunction with a random access memory, operating according toinstructions stored on a computer readable medium.

As shown in FIG. 3 , the TRP 10 also includes a network interface 50which connects to the DU 42 via a physical interface 16. The networkinterface 50 therefore provides a communication link for data andsignalling traffic from the TRP 10 via the DU 42 and the CU 40 to thecore network 20.

The interface 46 between the DU 42 and the CU 40 is known as the F1interface which can be a physical or a logical interface. The F1interface 46 between CU and DU may operate in accordance withspecifications 3GPP TS 38.470 and 3GPP TS 38.473, and may be formed froma fibre optic or other wired high bandwidth connection. In one examplethe connection 16 from the TRP 10 to the DU 42 is via fibre optic. Theconnection between a TRP 10 and the core network 20 can be generallyreferred to as a backhaul, which comprises the interface 16 from thenetwork interface 50 of the TRP 10 to the DU 42 and the F1 interface 46from the DU 42 to the CU 40.

Example arrangements of the present technique can be formed from awireless communications network corresponding to that shown in FIG. 1 or2 , as shown in FIG. 4 . FIG. 4 provides an example in which cells of awireless communications network are formed from infrastructure equipmentwhich are provided with an Integrated Access and Backhaul (IAB)capability. The wireless communications network 100 comprises the corenetwork 20 and a first, a second, a third and a fourth communicationsdevice (respectively 101, 102, 103 and 104) which may broadly correspondto the communications devices 4, 14 described above.

The wireless communications network 100 comprises a radio accessnetwork, comprising a first infrastructure equipment 110, a secondinfrastructure equipment 111, a third infrastructure equipment 112, anda fourth infrastructure equipment 113. Each of the infrastructureequipment provides a coverage area (i.e. a cell, not shown in FIG. 4 )within which data can be communicated to and from the communicationsdevices 101 to 104. For example, the fourth infrastructure equipment 113provides a cell in which the third and fourth communications devices 103and 104 may obtain service. Data is transmitted from the fourthinfrastructure equipment 113 to the fourth communications device 104within its respective coverage area (not shown) via a radio downlink.Data is transmitted from the fourth communications device 104 to thefourth infrastructure equipment 113 via a radio uplink.

The infrastructure equipment 110 to 113 in FIG. 4 may correspond broadlyto the TRPs 10 of FIG. 2 and FIG. 3 .

The first infrastructure equipment 110 in FIG. 4 is connected to thecore network 20 by means of one or a series of physical connections. Thefirst infrastructure equipment 110 may comprise the TRP 10 (having thephysical connection 16 to the DU 42) in combination with the DU 42(having a physical connection to the CU 40 by means of the F1 interface46) and the CU 40 (being connected by means of a physical connection tothe core network 20).

However, there is no direct physical connection between any of thesecond infrastructure equipment 111, the third infrastructure equipment112, and the fourth infrastructure equipment 113 and the core network20. As such, it may be necessary (or, otherwise determined to beappropriate) for data received from a communications device (i.e. uplinkdata), or data for transmission to a communications device (i.e.downlink data) to be transmitted to or from the core network 20 viaother infrastructure equipment (such as the first infrastructureequipment 110) which has a physical connection to the core network 20,even if the communications device is not currently served by the firstinfrastructure equipment 110 but is, for example, in the case of thewireless communications device 104, served by the fourth infrastructureequipment 113.

The second, third and fourth infrastructure equipment 111 to 113 in FIG.4 may each comprise a TRP, broadly similar in functionality to the TRPs10 of FIG. 2 .

In some arrangements of the present technique, one or more of the secondto fourth infrastructure equipment 111 to 113 in FIG. 4 may furthercomprise a DU 42, and in some arrangements of the present technique, oneor more of the second to fourth infrastructure equipment 110 to 113 maycomprise a DU and a CU.

In some arrangements of the present technique, the CU 40 associated withthe first infrastructure equipment 110 may perform the function of a CUnot only in respect of the first infrastructure equipment 110, but alsoin respect of one or more of the second, the third and the fourthinfrastructure equipment 111 to 113.

In order to provide the transmission of the uplink data or the downlinkdata between a communications device and the core network, a route isdetermined by any suitable means, with one end of the route being aninfrastructure equipment physically connected to a core network and bywhich uplink and downlink traffic is routed to or from the core network.

In the following, the term ‘node’ is used to refer to an entity orinfrastructure equipment which forms a part of a route for thetransmission of the uplink data or the downlink data.

An infrastructure equipment which is physically connected to the corenetwork and operated in accordance with an example arrangement mayprovide communications resources to other infrastructure equipment andso is referred to as a ‘donor node’. An infrastructure equipment whichacts as an intermediate node (i.e. one which forms a part of the routebut is not acting as a donor node) is referred to as a ‘relay node’. Itshould be noted that although such intermediate node infrastructureequipment act as relay nodes on the backhaul link, they may also provideservice to communications devices. The relay node at the end of theroute which is the infrastructure equipment controlling the cell inwhich the communications device is obtaining service is referred to asan ‘end node’.

In the wireless network illustrated in FIG. 4 , each of the first tofourth infrastructure equipment 110 to 113 may therefore function asnodes. For example, a route for the transmission of uplink data from thefourth communications device 104 may consist of the fourthinfrastructure equipment 113 (acting as the end node), the thirdinfrastructure equipment 112 (acting as a relay node), and the firstinfrastructure equipment 110 (acting as the donor node). The firstinfrastructure 110, being connected to the core network 20, transmitsthe uplink data to the core network 20.

For clarity and conciseness in the following description, the firstinfrastructure equipment 110 is referred to below as the ‘donor node’,the second infrastructure equipment 111 is referred to below as ‘Node1’, the third infrastructure equipment 112 is referred to below as ‘Node2’ and the fourth infrastructure equipment 113 is referred to below as‘Node 3’.

For the purposes of the present disclosure, the term ‘upstream node’ isused to refer to a node acting as a relay node or a donor node in aroute, which is a next hop when used for the transmission of data viathat route from a wireless communications device to a core network.Similarly, ‘downstream node’ is used to refer to a relay node from whichuplink data is received for transmission to a core network. For example,if uplink data is transmitted via a route comprising (in order) the Node3 113, the Node 1 111 and the donor node 110, then the donor node 110 isan upstream node with respect to the Node 1 111, and the Node 3 113 is adownstream node with respect to the Node 1 111.

More than one route may be used for the transmission of the uplink datafrom a given communications device; this is referred to herein as‘multi-connectivity’. For example, the uplink data transmitted by thewireless communications device 104 may be transmitted either via theNode 3 113 and the Node 2 112 to the donor node 110, or via the Node 3113 and the Node 1 111 to the donor node 110.

In the following description, example arrangements are described inwhich each of the nodes is an infrastructure equipment; the presentdisclosure is not so limited. A node may comprise at least atransmitter, a receiver and a controller. In some arrangements of thepresent technique, the functionality of a node (other than the donornode) may be carried out by a communications device, which may be thecommunications device 4 (of FIG. 1 ) or 14 (of FIG. 2 ), adaptedaccordingly. As such, in some arrangements of the present technique, aroute may comprise one or more communications devices. In otherarrangements, a route may consist of only a plurality of infrastructureequipment.

In some arrangements of the present technique, an infrastructureequipment acting as a node may not provide a wireless access interfacefor the transmission of data to or by a communications device other thanas part of an intermediate transmission along a route.

In some arrangements of the present technique, a route is definedconsidering a wireless communications device (such as the wirelesscommunications device 104) as the start of a route. In otherarrangements a route is considered to start at an infrastructureequipment which provides a wireless access interface for thetransmission of the uplink data by a wireless communications device.

Each of the first infrastructure equipment acting as the donor node 110and the second to fourth infrastructure equipment acting as the Nodes1-3 111-113 may communicate with one or more other nodes by means of aninter-node wireless communications link, which may also be referred toas a wireless backhaul communications links. For example, FIG. 4illustrates four inter-node wireless communications links 130, 132, 134,136.

Each of the inter-node wireless communications links 130, 132, 134, 136may be provided by means of a respective wireless access interface.Alternatively, two or more of the inter-node wireless communicationslinks 130, 132, 134, 136 may be provided by means of a common wirelessaccess interface and in particular, in some arrangements of the presenttechnique, all of the inter-node wireless communications links 130, 132,134, 136 are provided by a shared wireless access interface.

A wireless access interface which provides an inter-node wirelesscommunications link may also be used for communications between aninfrastructure equipment (which may be a node) and a communicationsdevice which is served by the infrastructure equipment. For example, thefourth wireless communications device 104 may communicate with theinfrastructure equipment Node 3 113 using the wireless access interfacewhich provides the inter-node wireless communications link 134connecting the Node 3 113 and the Node 2 112.

The wireless access interface(s) providing the inter-node wirelesscommunications links 130, 132, 134, 136 may operate according to anyappropriate specifications and techniques. In some arrangements of thepresent technique, a wireless access interface used for the transmissionof data from one node to another uses a first technique and a wirelessaccess interface used for the transmission of data between aninfrastructure equipment acting as a node and a communications devicemay use a second technique different from the first. In somearrangements of the present technique, the wireless access interface(s)used for the transmission of data from one node to another and thewireless access interface(s) used for the transmission of data betweenan infrastructure equipment and a communications device use the sametechnique.

Examples of wireless access interface standards include the thirdgeneration partnership project (3GPP)-specified GPRS/EDGE (“2G”), WCDMA(UMTS) and related standards such as HSPA and HSPA+ (“3G”), LTE andrelated standards including LTE-A (“4G”), and NR (“5G”).

Techniques that may be used to provide a wireless access interfaceinclude one or more of TDMA, FDMA, OFDMA, SC-FDMA, CDMA. Duplexing (i.e.the transmission over a wireless link in two directions) may be by meansof frequency division duplexing (FDD) or time division duplexing (TDD)or a combination of both.

In some arrangements of the present technique, two or more of theinter-node wireless communications links 130, 132, 134, 136 may sharecommunications resources. This may be because two or more of theinter-node wireless communications links 130, 132, 134, 136 are providedby means of a single wireless access interface or because two or more ofthe inter-node wireless communications links 130, 132, 134, 136nevertheless operate simultaneously using a common range of frequencies.

The nature of the inter-node wireless communications links 130, 132,134, 136 may depend on the architecture by which the wireless backhaulfunctionality is achieved.

Integrated Access and Backhaul (IAB) for NR

A new study item on Integrated Access and Backhaul for NR [3] has beenapproved. Several requirements and aspects for the integrated access andwireless backhaul for NR to address are discussed in [3], which include:

-   -   Efficient and flexible operation for both inband and outband        relaying in indoor and outdoor scenarios;    -   Multi-hop and redundant connectivity;    -   End-to-end route selection and optimisation;    -   Support of backhaul links with high spectral efficiency;    -   Support of legacy NR UEs.

The stated objective of the study detailed in [3] is to identify andevaluate potential solutions for topology management forsingle-hop/multi-hop and redundant connectivity, route selection andoptimisation, dynamic resource allocation between the backhaul andaccess links, and achieving high spectral efficiency while alsosupporting reliable transmission.

FIG. 5 shows the scenario presented in [3], where a backhaul link isprovided from cell site A 501 to cells B 502 and C 504 over the air. Itis assumed that cells B 502 and C 504 have no wired backhaulconnectivity. Considering the CU/DU split architecture in NR asdescribed above, it can be assumed that all of cells A 501, B 502 and C504 have a dedicated DU unit and are controlled by the same CU.

Several architecture requirements for IAB are laid out in [4]. Theseinclude the support for multiple backhaul hops, that topology adaptationfor physically fixed relays shall be supported to enable robustoperation, minimisation of impact to core network specifications,consideration of impact to core networking signalling load, and Release15 NR specifications should be reused as much as possible in the designof the backhaul link, with enhancements considered.

FIG. 6 is reproduced from [5], and shows an example of a wirelesscommunications system comprising a plurality of IAB-enabled nodes, whichmay for example be TRPs forming part of an NR network. These comprise anIAB donor node 601 which has a connection to the core network, two IABnodes (a first IAB node 602 and a second IAB node 604) which havebackhaul connections to the IAB donor node 601, and a third IAB node 606(or end IAB node) which has a backhaul connection to each of the firstIAB node 602 and the second IAB node 604. Each of the first IAB node 601and third IAB node 606 have wireless access connections to UEs 608 and610 respectively. As shown in FIG. 6 , originally the third IAB node 606may communicate with the IAB donor node 601 via the first IAB node 602.After the second IAB node 604 emerges, there are now two candidateroutes from the third IAB node 606 to the IAB donor node 601; via thefirst IAB node 602 and via the new second IAB node 604. The newcandidate route via the second IAB node 604 will play an important rolewhen there is a blockage in the first IAB node 602 to IAB donor node 604link. Hence, knowing how to manage the candidate routes efficiently andeffectively is important to ensure timely data transmission betweenrelay nodes, especially when considering the characteristics of wirelesslinks.

Various architectures have been proposed in order to provide the IABfunctionality. The below described embodiments of the present techniqueare not restricted to a particular architecture. However, a number ofcandidate architectures which have been considered in, for example, 3GPPdocument [6] are described below.

FIG. 7 illustrates one possible architecture by which the donor Node110, the Node 1 111 and the Node 3 113 may provide a wireless backhaulto provide connectivity for the UEs 104, 101, 14.

In FIG. 7 , each of the infrastructure equipment acting as an IAB nodes111, 113 and the donor node 110, includes a distributed unit (DU) 42,711, 731 which communicates with the UEs 14, 101, 104 and (in the caseof the DUs 42, 511 associated with the donor node 110 and the Node 1111) with the respective downstream IAB nodes 111, 113. Each of the IABnodes 111, 113 (not including the donor node 110) includes a mobileterminal (MT) 712, 732, which includes a transmitter and receiver (notshown) for transmitting and receiving data to and from the DU of anupstream IAB node and an associated controller (not shown). Theinter-node wireless communications links 130, 136 may be in the form ofnew radio (NR) “Uu” wireless interface. The mobile terminals 712, 732may have substantially the same functionality as a UE, at least at theaccess stratum (AS) layer. Notably, however, an MT may not have anassociated subscriber identity module (SIM) application; a UE may beconventionally considered to be the combination of an MT and a SIMapplication.

The Uu wireless interfaces used by IAB nodes to communicate with eachother may also be used by UEs to transmit and receive data to and fromthe DU of the upstream IAB node. For example, the Uu interface 720 whichis used by the Node 1 111 for communication with the donor node 110 mayalso be used by the UE 14 to transmit and receive data to and from thedonor node 110.

Similarly, an end node (such as the Node 3 113) may provide a Uuwireless interface 722 for the fourth UE 104 to communicate with the DU731 of the Node 3 113.

Alternative candidate architectures for the provision of IAB areprovided in FIG. 8 and FIG. 9 . In both FIG. 8 and FIG. 9 , each IABnode includes a gNB function, providing a wireless access interface forthe use of downstream IAB nodes and wireless communications devices.FIG. 9 differs from FIG. 7 in that, in FIG. 7 , PDU sessions areconnected end-on-end to form the wireless backhaul; in FIG. 9 , PDUsessions are encapsulated so that each IAB node may establish anend-to-end PDU session which terminates at the IAB donor node 110.

Given the vulnerable characteristics of wireless links, and consideringmulti-hops on the backhaul link, topology adaptation should beconsidered in the case that blockages or congestion occur in thebackhaul link considering a given hop. It is therefore imperative tomaximise the spectral efficiency of the backhaul link in order tomaximise its capacity. Embodiments of the present technique seek toaddress how the capacity of the backhaul link can be increased.

In FIG. 6 , only the IAB Donor gNB 601 has a fixed line backhaul intothe core network. It should be assumed in this case that the trafficfrom all the UEs 610 within the third IAB node's 606 coverage isbackhauled firstly to the first IAB node 602. This backhaul link mustcompete for capacity on the component carrier serving the first IAB Node602 with all the UEs 608 within the coverage area of the first IAB Node602. In the relevant art, the first IAB Node 602 in such a system asthat of FIG. 6 is called a “hop”—it relays communications between theend (third) IAB node 606 and the donor IAB node 601. The backhaul linkto the first IAB Node 602 requires enough capacity to support thetraffic from all the UEs 610, bearing in mind that some of these mayhave stringent QoS requirements that translate into high trafficintensities.

Even more challenging is that the last hop in the backhaul link, such asthat between the first IAB Node 602 and the IAB Donor node 601 now haseven more stringent capacity needs since it has to backhaul UE trafficfrom both groups of UEs 608 and 610. Embodiments of the presenttechnique are directed to increasing as much as possible the spectralefficiency in the use of the limited radio resources assigned forbackhaul, so as to mitigate the capacity crunch on the IAB backhaul.

Spectral Efficiency for the IAB Links in NR

FIG. 10 shows a part schematic, part message flow diagram ofcommunications in a wireless communications network 1000 in accordancewith embodiments of the present technique. The wireless communicationsnetwork 1000 comprises a plurality of infrastructure equipment 1002,1004, 1006, 1008 each being configured to communicate with one or moreothers of the infrastructure equipment 1002, 1004, 1006, 1008 via abackhaul communications link 1012, one or more of the infrastructureequipment 1002, 1004, 1006, 1008 each being configured to communicatewith one or more communications devices 1020 via an access link 1014. Afirst of the infrastructure equipment 1002 is configured to act as adonor node connected to a core network part 1001 of the wirelesscommunications network 1000 and comprises transceiver circuitry 1002 aand controller circuitry 1002 b configured in combination to receive1030, at the first infrastructure equipment 1002, signals representingdata from one or more others of the infrastructure equipment 1004, 1006,1008 the data having been received at the one or more others of theinfrastructure equipment 1004, 1006, 1008 from one or more of thecommunications devices 1020 or from other infrastructure equipment 1004,1006, 1008, and to transmit 1040, by the first infrastructure equipment1002, the data from the one or more others of the infrastructureequipment 1004, 1006, 1008 to the core network part 1001 of the wirelesscommunications network 1000, wherein at least one of the infrastructureequipment 1002, 1004, 1006, 1008 is configured to use at least onespectral efficiency enhancing technique to receive the signals, the atleast one spectral efficiency enhancing technique allowing the at leastone infrastructure equipment 1002, 1004, 1006, 1008 to receive thesignals in the backhaul communications link, the at least one spectralefficiency enhancing technique not allowing the at least oneinfrastructure equipment 1002, 1004, 1006, 1008 to receive the signalsin the access link.

All of the IAB relay nodes shown in FIG. 6 (such as the third IAB Node606), the hop nodes (such as the first IAB Node 602) and donor nodes(e.g. node 601) are gNBs that are physically fixed and not moving. It istherefore expected that the backhaul link between the end node and thehop or donor nodes would essentially be fixed. Such fixed links maypotentially have a line of sight (LoS) as well. As the link is fixed,propagation conditions can be significantly improved by use of beamforming. Beam forming focuses all the power of the signal in a thin beamto maximize its directivity. In other words, the at least one spectralefficiency enhancing technique comprises receiving the signals using oneor more beams, beam-formed specifically for the purpose, in which powerof each of the signals is focused, each of the one or more beams beingseparately identifiable and forming a directional bias with respect tothe at least one infrastructure equipment.

In this arrangement, the fact that the beam forming increases thetransmitter directivity and so reduces the impact of free space loss isexploited, leading to a high signal to interference and noise powerratio (SINR) at the IAB backhaul link receiver. In this arrangement, ahigh order modulation and coding scheme (MCS) that incorporates higherorder modulation schemes such as 2^(m)-QAM where m has a value of 10 ormore and higher Forward Error Code (FEC) code rates are used for suchlinks. With such MCS with 2^(m)-QAM modulation and r code rate, eachresource element (RE) allocated to the backhaul link will carry as manyas rm information bits, increasing proportionately as either m or r isincreased and so maximize the spectral efficiency of the backhaulbecause of the benign propagation conditions. In other words, the datamay be modulated onto the signals with a higher order modulation schemethan if the at least one spectral efficiency enhancing technique was notused to receive the signals. The signals may be transmitted with ahigher code rate than if the at least one spectral efficiency enhancingtechnique was not used to receive the signals.

In another arrangement, spectral efficiency of the backhaul linkespecially from one hop to the next is improved by increasing the sizeof transmission resources that can be allocated in a resource allocationevent. This is achieved through slot aggregation. In other words, the atleast one spectral efficiency enhancing technique comprisestransmitting, by the at least one infrastructure equipment to the one ormore other infrastructure equipment, an indication that the one or moreother infrastructure equipment may allocate a larger amount of radioresources for the backhaul communications link than compared to theradio resources for the access link, the larger amount of radioresources being allocated by aggregating a plurality of smaller units ofradio resources.

Slot aggregation builds bigger transmission slots comprised of aplurality of slots. For example, while a normal slot may be configuredas comprised of a certain number of subcarriers (e.g. 12 subcarriers)over N symbols, an aggregated slot in Rel 15 NR may comprise 2, 4, or 8such normal slots and so lasts for 2N, 4N, or 8N symbols as the case maybe. In Rel 15 NR, a slot in a time domain consists of 14 symbols (i.e.N=14). Slot aggregation allows the carriage of larger transmissionblocks, thereby saving the resources that may have been used for, say,the multiple slot header information of the aggregated normal slots suchas the PDCCH and a group-common PDCCH conveying a slot formatinformation (SFI) etc. to be used for the traffic channels, furthermaximizing the spectral efficiency. Rel 15 NR allows slot aggregationonly for the down-link (DL). This arrangement also includes slotaggregation on the up-link (UL) since the capacity crunch on thebackhaul link is present both for the DL and the UL.

Furthermore, it is possible to configure different slot aggregationfactors for the DL and the UL. For example, in a session when a UEconnected to the end node is streaming video from the Internet, the DLtraffic flow is more intensive than the UL traffic flow which in thiscase may simply be made up of interactive commands such as PAUSE, PLAYetc. In this example, the down backhaul link (donor to hop or end node)could be configured to use a higher slot aggregation factor of 8 whilethe up backhaul link (end node to hop or donor node) could be configuredto use a lower slot aggregation factor of 2. The situation could bereversed with a lower aggregation factor for the DL than the UL insessions in which the said UE is uploading video clips to a website forexample. Furthermore, the configurable number of aggregated slots can beincreased for the down backhaul link and the up backhaul link. Forexample, while the configurable number of aggregated slots forconventional downlink (i.e. access link) is chosen from a listcomprising {2, 4, 8}, the list of configurable number of slots for thedown/up backhaul link can be different and include larger numbers forexample {4,8,16,32}. Limiting to not more than 4 entries allows the samenumber of signalling bits to be used both for the access and backhaullinks. The list can be made longer such as {2,4,8,16,32,64,128,256}.However, this requires an increase of one bit in the configurationsignalling field. With an extended or new list for configuring theaggregation factor of the backhaul link, larger aggregation factors aremade available for configuring the backhaul link.

In another arrangement, the fact that the highly directive signalproduced by a technique such as beam forming results in very littlemultipath at the receiver is exploited. Furthermore, the stationarity ofboth the transmitter and receiver at each end of the backhaul link alsomeans that there is very little time variation to the power of thesignal at the antenna of the receiver. This arrangement exploits the lowfrequency selectivity (due to the reduced multipath) and the lack oftime variation on the channel to reduce the density of the referencesymbols such as sounding reference signals (SRS) or demodulationreference signals (DM-RS) transmitted for use in channel estimation fora physical channel (for example, a physical downlink shared channel(PDSCH) and a physical uplink shared channel (PUSCH)) in the backhaullink. In other words, the at least one spectral efficiency enhancingtechnique comprises transmitting the signals by the one or more othersof the infrastructure equipment and/or the one or more of thecommunications devices with a smaller density DM-RS in the frequencydomain on the backhaul communications link than compared to on theaccess link.

For example, if the DM-RS frequency domain density for the access linkis 1 in 4 subcarriers and compared to the access link, the multipathdelay spread is halved on the backhaul link, then the DM-RS frequencydomain density can be reduced by half to 1 in 8 subcarriers for thebackhaul link. Rel-15 NR defines two configurable DM-RS densities forthe access link: 1 in 4 and 1 in 6 subcarriers in the frequency domain.Lower densities will be defined for the backhaul such as 1 in N₁ and 1in N₂ where N₁=4K and N₂=8K where K is a small integer. In addition,lower densities will be defined such as 1 in 12K subcarriers where K isa small integer (i.e. 1 in K resource block). The density of DM-RSdetermines the maximum number of layers for MIMO (spatial) multiplexing.The reduced density can be exploited to increase the number of spatiallayers in the backhaul links. In other words, the at least one spectralefficiency enhancing technique comprises increasing a maximum number oflayers onto which the signals can be multiplexed in the backhaul linksusing a multiple-input and multiple-output, MIMO, multiplexing process.In the current 3GPP specifications, where DM-RS densities can beconfigured to be 1 in 4 or 1 in 6, the maximum layers are 8 and 12respectively. Therefore when the lower densities are configured forbackhaul link, the maximum layers can be increased. For example, whenDM-RS density is 1 in X subcarriers, the maximum layers can be 2X. TheDM-RS density on the backhaul link in the frequency domain can be fixedto the lowest density from a plurality of predefined, configurabledensities on the access link.

Further, slot aggregation produces long slots with many DM-RS in thetime domain. This arrangement also benefits from the low time variationin the channel to reduce the time domain density of DM-RS. In Rel-15 NR,the number of positions for DL time domain DM-RS can be 1, 2, 3 and 4within 1 slot (14 symbols). In other words, the at least one spectralefficiency enhancing technique comprises transmitting the signals by theone or more others of the infrastructure equipment with a smallerdensity of demodulation reference signals, DM-RS, in the time domain onthe backhaul communications link than compared to on the access link. Inthis arrangement and taking into account increased slot aggregation, theconfigurable number of positions can be restricted to only 1 forbackhaul link (i.e. RRC parameter “DL-DMRS-add-pos” can be configuredwith only 1). Furthermore, while DM-RS for the access link in the Rel 15NR is mapped in every slot even in the case of the slot aggregation,DM-RS for backhaul link with slot aggregation can be reduced in timedomain. For example, when Y slots are aggregated for backhaul link, thenumber of positions for time domain DM-RS can be less than Y (e.g. 1)within Y aggregated slots. The number of positions can be implicitlydetermined by the number of aggregated slots or can be explicitlysignalled for example, via an RRC parameter and/or a downlink controlinformation (DCI) which is conveyed by PDCCH. The DM-RS density on thebackhaul link in the time domain can also be fixed to the lowest densityfrom a plurality of pre-defined, configurable densities available foruse in the access link. This has the advantage of limiting changes inthe Rel 15 signalling.

The above described arrangements—especially the ones related to DM-RSdensity reduction are based on orthogonal frequency or orthogonal timeIAB-access resource partitioning schemes between backhaul and accesslinks such as TDM and FDM in the same specific resource such as acomponent carrier (CC) or a bandwidth part (BWP). The DM-RS densityreduction arrangements may be not suitable for space divisionmultiplexing (SDM) schemes such as MU-MIMO in which SDM is appliedbetween access and backhaul. In other words, radio resources for thebackhaul link and radio resources for the access link may be separatedfrom one another in either or both of the time domain and the frequencydomain. The above described arrangements may also be applied to SDM.Resources may be preferentially allocated for the backhaul link over theaccess link.

Flow Chart Representation

FIG. 11 shows a flow diagram illustrating a process of communications ina communications system in accordance with embodiments of the presenttechnique. The process shown by FIG. 11 is a method of controllingcommunications within a wireless communications network comprising aplurality of infrastructure equipment each being configured tocommunicate with one or more others of the infrastructure equipment viaa backhaul communications link, one or more of the infrastructureequipment each being configured to communicate with one or morecommunications devices via an access link.

The method begins in step S1101. The method comprises, in step S1102,receiving, at a first of the infrastructure equipment acting as a donornode connected to a core network part of the wireless communicationsnetwork, signals representing data from one or more others of theinfrastructure equipment, the data having been received at the one ormore others of the infrastructure equipment from one or more of thecommunications devices or from other infrastructure equipment. At leastone of the infrastructure equipment uses at least one spectralefficiency enhancing technique to receive the signals, the at least onespectral efficiency enhancing technique allowing the at least oneinfrastructure equipment to receive the signals in the backhaulcommunications link, the at least one spectral efficiency enhancingtechnique not allowing the at least one infrastructure equipment toreceive the signals in the access link. The process proceeds to stepS1104, which comprises t transmitting, by the first infrastructureequipment, the data from the one or more others of the infrastructureequipment to the core network part of the wireless communicationsnetwork. The process ends in step S1106.

Those skilled in the art would appreciate that the method shown by FIG.11 may be adapted in accordance with embodiments of the presenttechnique. For example, other intermediate steps may be included in themethod, or the steps may be performed in any logical order. Inparticular, the at least one spectral efficiency enhancing techniqueused for communication between the donor node and the one or more othersof the infrastructure equipment would have been originally configuredfor use during the initial setup of the backhaul link either when thedownstream node was originally turned on or when the current sessionstarted or as part of radio link adaptation process. The at least onespectral efficiency enhancing technique may be used for the linksbetween any two infrastructure equipment in the wireless communicationsnetwork. For example, this may be between the donor node and end node,donor node and a hop (relay) node, two hop nodes, or a hop node and endnode.

Though embodiments of the present technique have been described largelyby way of the example system shown in FIG. 10 , it would be clear tothose skilled in the art that they could be equally applied to othersystems, where for example there may be many more nodes or paths tochoose from, or more hops between the donor and end nodes.

Those skilled in the art would also appreciate that such infrastructureequipment and/or wireless communications networks as herein defined maybe further defined in accordance with the various arrangements andembodiments discussed in the preceding paragraphs. It would be furtherappreciated by those skilled in the art that such infrastructureequipment and wireless communications networks as herein defined anddescribed may form part of communications systems other than thosedefined by the present invention.

The following numbered paragraphs provide further example aspects andfeatures of the present technique:

Paragraph 1. A method of controlling communications within a wirelesscommunications network comprising a plurality of infrastructureequipment each being configured to communicate with one or more othersof the infrastructure equipment via a backhaul communications link, oneor more of the infrastructure equipment each being configured tocommunicate with one or more communications devices via an access link,the method comprising

-   -   receiving, at a first of the infrastructure equipment acting as        a donor node connected to a core network part of the wireless        communications network, signals representing data from one or        more others of the infrastructure equipment, the data having        been received at the one or more others of the infrastructure        equipment from one or more of the communications devices or from        other infrastructure equipment, and    -   transmitting, by the first infrastructure equipment, the data        from the one or more others of the infrastructure equipment to        the core network part of the wireless communications network,    -   wherein at least one of the infrastructure equipment uses at        least one spectral efficiency enhancing technique to receive the        signals, the at least one spectral efficiency enhancing        technique allowing the at least one infrastructure equipment to        receive the signals in the backhaul communications link, the at        least one spectral efficiency enhancing technique not allowing        the at least one infrastructure equipment to receive the signals        in the access link.

Paragraph 2. A method according to Paragraph 1, wherein the at least onespectral efficiency enhancing technique comprises receiving the signalsusing one or more beams in which power of each of the signals isfocused, each of the one or more beams being separately identifiable andforming a directional bias with respect to the at least oneinfrastructure equipment.

Paragraph 3. A method according to Paragraph 2, wherein the data ismodulated onto the signals with a higher order modulation scheme than ifthe at least one spectral efficiency enhancing technique was not used toreceive the signals.

Paragraph 4. A method according to Paragraph 2 or Paragraph 3, whereinthe signals are transmitted with a higher code rate than if the at leastone spectral efficiency enhancing technique was not used to receive thesignals.

Paragraph 5. A method according to any of Paragraphs 1 to 4, wherein theat least one spectral efficiency enhancing technique comprisestransmitting, by the at least one infrastructure equipment to the one ormore other infrastructure equipment, an indication that the one or moreother infrastructure equipment may allocate a larger amount of radioresources for the backhaul communications link than compared to theradio resources for the access link, the larger amount of radioresources being allocated by aggregating a plurality of smaller units ofradio resources.

Paragraph 6. A method according to any of Paragraphs 1 to 5, wherein theat least one spectral efficiency enhancing technique comprisestransmitting the signals by the one or more others of the infrastructureequipment and/or the one or more of the communications devices with asmaller density of demodulation reference signals, DM-RS, in thefrequency domain on the backhaul communications link than compared to onthe access link

Paragraph 7. A method according to Paragraph 5 or Paragraph 6, whereinthe at least one spectral efficiency enhancing technique comprisesincreasing a maximum number of layers onto which the signals can bemultiplexed using a multiple-input and multiple-output, MIMO,multiplexing process.

Paragraph 8. A method according to Paragraph 6 or Paragraph 7, whereinthe at least one spectral efficiency enhancing technique comprisestransmitting the signals on the backhaul communications link with asmallest DM-RS density of a plurality of predefined DM-RS densities ofthe access link.

Paragraph 9. A method according to any of Paragraphs 1 to 8, wherein theat least one spectral efficiency enhancing technique comprisestransmitting the signals by the one or more others of the infrastructureequipment with a smaller density of demodulation reference signals,DM-RS, in the time domain on the backhaul communications link thancompared to on the access link.

Paragraph 10. A method according to Paragraph 9, wherein the at leastone spectral efficiency enhancing technique comprises transmitting thesignals on the backhaul communications link with a smallest time domainDM-RS density of a plurality of predefined time domain DM-RS densitiesof the access link.

Paragraph 11. A method according to any of Paragraphs 1 to 10, whereinradio resources for the backhaul communications link and radio resourcesfor the access link are separated from one another in the frequencydomain.

Paragraph 12. A method according to any of Paragraphs 1 to 11, whereinradio resources for the backhaul communications link and radio resourcesfor the access link are separated from one another in the time domain.

Paragraph 13. A wireless communications network comprising a pluralityof infrastructure equipment each being configured to communicate withone or more others of the infrastructure equipment via a backhaulcommunications link, one or more of the infrastructure equipment eachbeing configured to communicate with one or more communications devicesvia an access link, wherein a first of the infrastructure equipment isconfigured to act as a donor node connected to a core network part ofthe wireless communications network and comprises transceiver circuitryand controller circuitry configured in combination

-   -   to receive, at the first infrastructure equipment, signals        representing data from one or more others of the infrastructure        equipment, the data having been received at the one or more        others of the infrastructure equipment from one or more of the        communications devices or from other infrastructure equipment,        and    -   to transmit, by the first infrastructure equipment, the data        from the one or more others of the infrastructure equipment to        the core network part of the wireless communications network,    -   wherein at least one of the infrastructure equipment is        configured to use at least one spectral efficiency enhancing        technique to receive the signals, the at least one spectral        efficiency enhancing technique allowing the at least one        infrastructure equipment to receive the signals in the backhaul        communications link, the at least one spectral efficiency        enhancing technique not allowing the at least one infrastructure        equipment to receive the signals in the access link.

Paragraph 14. Circuitry for a wireless communications network comprisinga plurality of infrastructure equipment each being configured tocommunicate with one or more others of the infrastructure equipment viaa backhaul communications link, one or more of the infrastructureequipment each being configured to communicate with one or morecommunications devices via an access link, wherein a first of theinfrastructure equipment is configured to act as a donor node connectedto a core network part of the wireless communications network andcomprises transceiver circuitry and controller circuitry configured incombination

-   -   to receive, at the first infrastructure equipment, signals        representing data from one or more others of the infrastructure        equipment, the data having been received at the one or more        others of the infrastructure equipment from one or more of the        communications devices or from other infrastructure equipment,        and    -   to transmit, by the first infrastructure equipment, the data        from the one or more others of the infrastructure equipment to        the core network part of the wireless communications network,    -   wherein at least one of the infrastructure equipment is        configured to use at least one spectral efficiency enhancing        technique to receive the signals, the at least one spectral        efficiency enhancing technique allowing the at least one        infrastructure equipment to receive the signals in the backhaul        communications link, the at least one spectral efficiency        enhancing technique not allowing the at least one infrastructure        equipment to receive the signals in the access link.

Paragraph 15. A method of operating a first infrastructure equipmentforming part of a wireless communications network comprising a pluralityof other infrastructure equipment, the first infrastructure equipmentand the plurality of other infrastructure equipment each beingconfigured to communicate with one or more others of the infrastructureequipment via a backhaul communications link, one or more of theinfrastructure equipment each being configured to communicate with oneor more communications devices via an access link, wherein the firstinfrastructure equipment is configured to act as a donor node connectedto a core network part of the wireless communications network, themethod comprising

-   -   receiving signals representing data from one or more others of        the infrastructure equipment, the data having been received at        the one or more others of the infrastructure equipment from one        or more of the communications devices or from other        infrastructure equipment, and    -   transmitting the data from the one or more others of the        infrastructure equipment to the core network part of the        wireless communications network,    -   wherein at least one of the infrastructure equipment uses at        least one spectral efficiency enhancing technique to receive the        signals, the at least one spectral efficiency enhancing        technique allowing the at least one infrastructure equipment to        receive the signals in the backhaul communications link, the at        least one spectral efficiency enhancing technique not allowing        the at least one infrastructure equipment to receive the signals        in the access link.

Paragraph 16. A first infrastructure equipment forming part of awireless communications network comprising a plurality of otherinfrastructure equipment, the first infrastructure equipment and theplurality of other infrastructure equipment each being configured tocommunicate with one or more others of the infrastructure equipment viaa backhaul communications link, one or more of the infrastructureequipment each being configured to communicate with one or morecommunications devices via an access link, wherein the firstinfrastructure equipment is configured to act as a donor node connectedto a core network part of the wireless communications network andcomprises transceiver circuitry and controller circuitry configured incombination

-   -   to receive signals representing data from one or more others of        the infrastructure equipment, the data having been received at        the one or more others of the infrastructure equipment from one        or more of the communications devices or from other        infrastructure equipment, and    -   to transmit the data from the one or more others of the        infrastructure equipment to the core network part of the        wireless communications network,    -   wherein at least one of the infrastructure equipment is        configured to use at least one spectral efficiency enhancing        technique to receive the signals, the at least one spectral        efficiency enhancing technique allowing the at least one        infrastructure equipment to receive the signals in the backhaul        communications link, the at least one spectral efficiency        enhancing technique not allowing the at least one infrastructure        equipment to receive the signals in the access link.

Paragraph 17. Circuitry for a first infrastructure equipment formingpart of a wireless communications network comprising a plurality ofother infrastructure equipment, the first infrastructure equipment andthe plurality of other infrastructure equipment each being configured tocommunicate with one or more others of the infrastructure equipment viaa backhaul communications link, one or more of the infrastructureequipment each being configured to communicate with one or morecommunications devices via an access link, wherein the firstinfrastructure equipment is configured to act as a donor node connectedto a core network part of the wireless communications network andcomprises transceiver circuitry and controller circuitry configured incombination

-   -   to receive signals representing data from one or more others of        the infrastructure equipment, the data having been received at        the one or more others of the infrastructure equipment from one        or more of the communications devices or from other        infrastructure equipment, and    -   to transmit the data from the one or more others of the        infrastructure equipment to the core network part of the        wireless communications network,    -   wherein at least one of the infrastructure equipment is        configured to use at least one spectral efficiency enhancing        technique to receive the signals, the at least one spectral        efficiency enhancing technique allowing the at least one        infrastructure equipment to receive the signals in the backhaul        communications link, the at least one spectral efficiency        enhancing technique not allowing the at least one infrastructure        equipment to receive the signals in the access link.

It will be appreciated that the above description for clarity hasdescribed embodiments with reference to different functional units,circuitry and/or processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, circuitry and/or processors may be used without detracting fromthe embodiments.

Described embodiments may be implemented in any suitable form includinghardware, software, firmware or any combination of these. Describedembodiments may optionally be implemented at least partly as computersoftware running on one or more data processors and/or digital signalprocessors. The elements and components of any embodiment may bephysically, functionally and logically implemented in any suitable way.Indeed the functionality may be implemented in a single unit, in aplurality of units or as part of other functional units. As such, thedisclosed embodiments may be implemented in a single unit or may bephysically and functionally distributed between different units,circuitry and/or processors.

Although the present disclosure has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognise that various features of the described embodimentsmay be combined in any manner suitable to implement the technique.

REFERENCES

-   [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based    radio access”, John Wiley and Sons, 2009.-   [2] RP-161901, “Revised work item proposal: Enhancements of NB-IoT”,    Huawei, HiSilicon, 3GPP TSG RAN Meeting #73, New Orleans, USA, Sep.    19-22, 2016.-   [3] RP-170831, “New SID Proposal: Study on Integrated Access and    Backhaul for NR”, AT&T, 3GPP RAN Meeting #75, Dubrovnik, Croatia,    March 2017.-   [4] 3GPP TTR 38.874 “3^(rd) Generation Partnership Project;    Technical Specification Group Radio Access Network; Study on    Integrated Access and Backhaul; (Release 15)”, 3^(rd) Generation    Partnership Project, February 2018.-   [5] R2-1801606, “Proposals on IAB Architecture”, Qualcomm et al,    3GPP TSG-RAN WG2 NR Ad hoc 1801, Vancouver, Canada, Jan. 22-26,    2018.-   [6] R3-181502, “Way Forward—IAB Architecture for L2/3 relaying”,    Qualcomm et al, 3GPP TSG RAN WG3 Meeting #99, 2018

1. A wireless communications network comprising a plurality ofinfrastructure equipment each being configured to communicate with oneor more others of the infrastructure equipment via a backhaulcommunications link, one or more of the infrastructure equipment eachbeing configured to communicate with one or more communications devicesvia an access link, wherein a first of the infrastructure equipment isconfigured to act as a donor node connected to a core network part ofthe wireless communications network and comprises transceiver circuitryand controller circuitry configured in combination: to receive, at thefirst infrastructure equipment, signals representing data from one ormore others of the infrastructure equipment, the data having beenreceived at the one or more others of the infrastructure equipment fromone or more of the communications devices or from other infrastructureequipment, and to transmit, by the first infrastructure equipment, thedata from the one or more others of the infrastructure equipment to thecore network part of the wireless communications network, wherein aninfrastructure equipment of the plurality of infrastructure equipment isconfigured to use at least one spectral efficiency enhancing techniqueto receive the signals, the at least one spectral efficiency enhancingtechnique allowing the infrastructure equipment to receive the signalsin the backhaul communications link, the at least one spectralefficiency enhancing technique not allowing the infrastructure equipmentto receive the signals in the access link.
 2. Circuitry for a wirelesscommunications network comprising a plurality of infrastructureequipment each being configured to communicate with one or more othersof the infrastructure equipment via a backhaul communications link, oneor more of the infrastructure equipment each being configured tocommunicate with one or more communications devices via an access link,wherein a first of the infrastructure equipment is configured to act asa donor node connected to a core network part of the wirelesscommunications network and comprises transceiver circuitry andcontroller circuitry configured in combination: to receive, at the firstinfrastructure equipment, signals representing data from one or moreothers of the infrastructure equipment, the data having been received atthe one or more others of the infrastructure equipment from one or moreof the communications devices or from other infrastructure equipment,and to transmit, by the first infrastructure equipment, the data fromthe one or more others of the infrastructure equipment to the corenetwork part of the wireless communications network, wherein aninfrastructure equipment of the plurality of infrastructure equipment isconfigured to use at least one spectral efficiency enhancing techniqueto receive the signals, the at least one spectral efficiency enhancingtechnique allowing the infrastructure equipment to receive the signalsin the backhaul communications link, the at least one spectralefficiency enhancing technique not allowing the infrastructure equipmentto receive the signals in the access link.
 3. Circuitry for a firstinfrastructure equipment forming part of a wireless communicationsnetwork comprising a plurality of other infrastructure equipment, thefirst infrastructure equipment and the plurality of other infrastructureequipment each being configured to communicate with one or more othersof the infrastructure equipment via a backhaul communications link, oneor more of the infrastructure equipment each being configured tocommunicate with one or more communications devices via an access link,wherein the first infrastructure equipment is configured to act as adonor node connected to a core network part of the wirelesscommunications network and comprises transceiver circuitry andcontroller circuitry configured in combination: to receive signalsrepresenting data from one or more others of the infrastructureequipment, the data having been received at the one or more others ofthe infrastructure equipment from one or more of the communicationsdevices or from other infrastructure equipment, and to transmit the datafrom the one or more others of the infrastructure equipment to the corenetwork part of the wireless communications network, wherein aninfrastructure equipment of the plurality of infrastructure equipment isconfigured to use at least one spectral efficiency enhancing techniqueto receive the signals, the at least one spectral efficiency enhancingtechnique allowing the infrastructure equipment to receive the signalsin the backhaul communications link, the at least one spectralefficiency enhancing technique not allowing the infrastructure equipmentto receive the signals in the access link.
 4. The wirelesscommunications network of claim 1, wherein the at least one spectralefficiency enhancing technique comprises receiving the signals using oneor more beams in which power of each of the signals is focused, each ofthe one or more beams being separately identifiable and forming adirectional bias with respect to the at least one infrastructureequipment.
 5. The wireless communications network of claim 4, whereinthe data is modulated onto the signals with a higher order modulationscheme than if the at least one spectral efficiency enhancing techniquewas not used to receive the signals.
 6. The wireless communicationsnetwork of claim 4, wherein the signals are transmitted with a highercode rate than if the at least one spectral efficiency enhancingtechnique was not used to receive the signals.
 7. The wirelesscommunications network of claim 1, wherein the at least one spectralefficiency enhancing technique comprises transmitting, by theinfrastructure equipment to the one or more other infrastructureequipment, an indication that the one or more other infrastructureequipment allocate, for the up-link and down-link, an increased amountof radio resources for the backhaul communications link than compared tothe radio resources for the access link, the increased amount of radioresources being allocated to the one or more other infrastructureequipment by aggregating a plurality of smaller units of radioresources.
 8. The wireless communications network of claim 1, whereinthe at least one spectral efficiency enhancing technique comprisestransmitting the signals by the one or more others of the infrastructureequipment and/or the one or more of the communications devices with asmaller density of demodulation reference signals, DM-RS, in thefrequency domain on the backhaul communications link than compared to onthe access link.
 9. The wireless communications network of claim 7,wherein the at least one spectral efficiency enhancing techniquecomprises increasing a maximum number of layers onto which the signalsare multiplexed using a multiple-input and multiple-output, MIMO,multiplexing process.
 10. The wireless communications network of claim8, wherein the at least one spectral efficiency enhancing techniquecomprises transmitting the signals on the backhaul communications linkwith a smallest DM-RS density of a plurality of predefined DM-RSdensities of the access link.
 11. The wireless communications network ofclaim 1, wherein the at least one spectral efficiency enhancingtechnique comprises transmitting the signals by the one or more othersof the infrastructure equipment with a smaller density of demodulationreference signals, DM-RS, in the time domain on the backhaulcommunications link than compared to on the access link.
 12. Thewireless communications network of claim 11, wherein the at least onespectral efficiency enhancing technique comprises transmitting thesignals on the backhaul communications link with a smallest time domainDM-RS density of a plurality of predefined time domain DM-RS densitiesof the access link.
 13. The wireless communications network of claim 1,wherein radio resources for the backhaul communications link and radioresources for the access link are separated from one another in thefrequency domain.
 14. The wireless communications network of claim 1,wherein radio resources for the backhaul communications link and radioresources for the access link are separated from one another in the timedomain.
 15. The circuitry for the first infrastructure equipment ofclaim 3, wherein the at least one spectral efficiency enhancingtechnique comprises receiving the signals using one or more beams inwhich power of each of the signals is focused, each of the one or morebeams being separately identifiable and forming a directional bias withrespect to the at least one infrastructure equipment.
 16. The circuitryfor the first infrastructure equipment of claim 15, wherein the data ismodulated onto the signals with a higher order modulation scheme than ifthe at least one spectral efficiency enhancing technique was not used toreceive the signals.
 17. The circuitry for the first infrastructureequipment of claim 15, wherein the signals are transmitted with a highercode rate than if the at least one spectral efficiency enhancingtechnique was not used to receive the signals.
 18. The circuitry for thefirst infrastructure equipment of claim 3, wherein the at least onespectral efficiency enhancing technique comprises transmitting, by theinfrastructure equipment to the one or more other infrastructureequipment, an indication that the one or more other infrastructureequipment allocate, for the up-link and down-link, an increased amountof radio resources for the backhaul communications link than compared tothe radio resources for the access link, the increased amount of radioresources being allocated to the one or more other infrastructureequipment by aggregating a plurality of smaller units of radioresources.
 19. The circuitry for the first infrastructure equipment ofclaim 3, wherein the at least one spectral efficiency enhancingtechnique comprises transmitting the signals by the one or more othersof the infrastructure equipment and/or the one or more of thecommunications devices with a smaller density of demodulation referencesignals, DM-RS, in the frequency domain on the backhaul communicationslink than compared to on the access link.
 20. The circuitry for thefirst infrastructure equipment of claim 18, wherein the at least onespectral efficiency enhancing technique comprises increasing a maximumnumber of layers onto which the signals are multiplexed using amultiple-input and multiple-output, MIMO, multiplexing process.